accounts/keystore: lock file cache during scan, minor polish

accounts/keystore/file_cache.go

@@ -0,0 +1,102 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package keystore
+
+import (
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/ethereum/go-ethereum/log"
+	set "gopkg.in/fatih/set.v0"
+)
+
+// fileCache is a cache of files seen during scan of keystore.
+type fileCache struct {
+	all     *set.SetNonTS // Set of all files from the keystore folder
+	lastMod time.Time     // Last time instance when a file was modified
+	mu      sync.RWMutex
+}
+
+// scan performs a new scan on the given directory, compares against the already
+// cached filenames, and returns file sets: creates, deletes, updates.
+func (fc *fileCache) scan(keyDir string) (set.Interface, set.Interface, set.Interface, error) {
+	t0 := time.Now()
+
+	// List all the failes from the keystore folder
+	files, err := ioutil.ReadDir(keyDir)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	t1 := time.Now()
+
+	fc.mu.Lock()
+	defer fc.mu.Unlock()
+
+	// Iterate all the files and gather their metadata
+	all := set.NewNonTS()
+	mods := set.NewNonTS()
+
+	var newLastMod time.Time
+	for _, fi := range files {
+		// Skip any non-key files from the folder
+		path := filepath.Join(keyDir, fi.Name())
+		if skipKeyFile(fi) {
+			log.Trace("Ignoring file on account scan", "path", path)
+			continue
+		}
+		// Gather the set of all and fresly modified files
+		all.Add(path)
+
+		modified := fi.ModTime()
+		if modified.After(fc.lastMod) {
+			mods.Add(path)
+		}
+		if modified.After(newLastMod) {
+			newLastMod = modified
+		}
+	}
+	t2 := time.Now()
+
+	// Update the tracked files and return the three sets
+	deletes := set.Difference(fc.all, all)   // Deletes = previous - current
+	creates := set.Difference(all, fc.all)   // Creates = current - previous
+	updates := set.Difference(mods, creates) // Updates = modified - creates
+
+	fc.all, fc.lastMod = all, newLastMod
+	t3 := time.Now()
+
+	// Report on the scanning stats and return
+	log.Debug("FS scan times", "list", t1.Sub(t0), "set", t2.Sub(t1), "diff", t3.Sub(t2))
+	return creates, deletes, updates, nil
+}
+
+// skipKeyFile ignores editor backups, hidden files and folders/symlinks.
+func skipKeyFile(fi os.FileInfo) bool {
+	// Skip editor backups and UNIX-style hidden files.
+	if strings.HasSuffix(fi.Name(), "~") || strings.HasPrefix(fi.Name(), ".") {
+		return true
+	}
+	// Skip misc special files, directories (yes, symlinks too).
+	if fi.IsDir() || fi.Mode()&os.ModeType != 0 {
+		return true
+	}
+	return false
+}